| C S Sales Management Limited | Wholesale & retail | 2002 |
| C.S. Gray (Builders) Limited | Construction | 1946 |
| C.T. Baker Builders Merchant Ltd | Professional & scientific | 1962 |
| C.T. Baker Limited | Wholesale & retail | 1900 |
| Caister Academic Press Limited | Information & communication | 2001 |
| Caligraving Limited | Manufacturing | 1956 |
| Calum Ward & Co. Limited | Professional & scientific | 2003 |
| Campbell & Tate Ltd | Financial services | 2002 |
| CAN Builders Limited | Construction | 2000 |
| Cannon (East Anglia) Limited | Water & waste | 2005 |
| Capital Tower Limited | Financial services | 1997 |
| Caponica Ltd | Wholesale & retail | 2004 |
| Carl & Co Drywall Ltd | Construction | 2006 |
| Carl Lynn Roofing Limited | Construction | 2006 |
| Carpets + Limited | Wholesale & retail | 2003 |
| Cassava Ltd | Administrative & support | 2007 |
| Castle Financial Services (East Anglia) Limited | | 1988 |
| Cavendish Hotel Ltd | Hospitality | 2021 |
| CBC Metal Merchants Limited | Wholesale & retail | 2003 |
| Cedarbrooke Ltd. | Manufacturing | 2007 |
| Centre for Research and Dissemination Limited | Professional & scientific | 2000 |
| Cfit Limited | Administrative & support | 2021 |
| Chadds Limited | Wholesale & retail | 1986 |
| Chanteclair Ltd | Real estate | 2010 |
| Chapelfield Children's Day Nursery Limited | Education | 1999 |
| Charles Kelly Properties Limited | Real estate | 2005 |
| Charollais Limited | Agriculture & fishing | 1988 |
| Chart House Holdings Limited | Financial services | 2025 |
| Chatsworth Flats Limited | Households | 1985 |
| Chbar Limited | Hospitality | 2007 |
| Check Your Security Limited | Administrative & support | 2005 |
| Chefs Collection Limited | Wholesale & retail | 2016 |
| Chic-Grit Limited | | 1955 |
| Chris Everard Photography Limited | Professional & scientific | 2003 |
| Chris Riches Transport Services Limited | Transport & logistics | 1999 |
| Chris Sopp Scaffolding Limited | Construction | 2004 |
| City Locks (Norwich) Limited | Professional & scientific | 2006 |
| Classic Team Lotus Limited | Manufacturing | 1993 |
| Clive Townshend Ltd | Wholesale & retail | 2003 |
| CNC Machine Tools Limited | Manufacturing | 2000 |
| Co-Operative Education East | Education | 2016 |
| Coach Holidays From Scotland Limited | Professional & scientific | 2005 |
| Coach Services Limited | Transport & logistics | 1947 |
| Coatfern Limited | Agriculture & fishing | 1997 |
| Cobb Thatching Limited | Construction | 2007 |
| Cobholm and Lichfield Child Care Centre (UK) Limited | Health & social care | 2003 |
| Coda Plastics Limited | Manufacturing | 1973 |
| Colegate Construction Limited | Wholesale & retail | 1984 |
| Colin Richardson Accountants Limited | Professional & scientific | 2003 |
| Combine Pallet Co. Limited | Manufacturing | 1969 |
| Composite Engineering and Design Ltd | Professional & scientific | 2007 |
| Compute (UK) Limited | Information & communication | 1997 |
| Conclomeg Construction Limited | Construction | 2007 |
| Conkers 4 Kids Ltd | Education | 2003 |
| Convenience First Limited | Wholesale & retail | 2005 |
| Cooke's Band Instruments Limited | Wholesale & retail | 1976 |
| Cooper and Elms Limited | Wholesale & retail | 2002 |
| Cooper Roller Bearings Company Limited | Manufacturing | 1982 |
| Coowin Investments Limited | Construction | 1959 |
| Cordmark Limited | Professional & scientific | 1948 |
| Corpusty Stores Ltd | Wholesale & retail | 2006 |
| Corston Business Services Ltd | Professional & scientific | 2007 |
| Corton Property Preservation Limited | Construction | 2007 |
| Courtenay Sport Limited | Wholesale & retail | 1999 |
| Courtyard Farm Limited | Agriculture & fishing | 1960 |
| Coverberry Limited | Professional & scientific | 1948 |
| Craft'D Limited | Wholesale & retail | 2020 |
| Cranberry Communications Ltd | Information & communication | 2001 |
| Creative Penguin Anglia Ltd | Information & communication | 2023 |
| Crescent Coaches Limited | Information & communication | 1990 |
| Cricketpix Limited | Professional & scientific | 1999 |
| Crisp Malting Limited | Extraterritorial | 1976 |
| Criterion Computers Limited | | 1981 |
| Croft House (Norwich) Limited | Households | 1987 |
| Cromer Electrical Limited | Construction | 1977 |
| Cromer Kebab and Pizza Takeaway Ltd | Hospitality | 2024 |
| Crown Close Management Limited | Extraterritorial | 2005 |
| Crystal Signature Homes Ltd | Construction | 2025 |
| CS3 Properties Holdings Ltd | Real estate | 2025 |
| CT MAC Property Holdings Ltd | Financial services | 2026 |
| CT MAC Property Ltd | Real estate | 2026 |
| Cubet Properties Ltd | Real estate | 2024 |
| Cubic Design and Construction Limited | Manufacturing | 2002 |
| Cursitor Energy Services Limited | Administrative & support | 2007 |
| CWA Developments Limited | Construction | 2007 |
| D & C Murrell 2021 Limited | Construction | 2021 |
| D a Browne & SON Limited | Wholesale & retail | 2007 |
| D C Gaskins Ltd | Wholesale & retail | 2003 |
| D G Waters & Sons Ltd | Agriculture & fishing | 2011 |
| D Newstead Building Limited | Construction | 2006 |
| D.E. Panels Limited | Manufacturing | 1992 |
| D.P. Services & Supplies Limited | Transport & logistics | 2006 |
| D.R. Grey (Norwich) Limited | Wholesale & retail | 1987 |
| D.S. Hobbs & SON Limited | Wholesale & retail | 1978 |
| D.V.S. Plating Limited | Manufacturing | 1983 |
| D.W. Moore & Co Limited | Financial services | 1969 |
| D.W. Rhodes (Farms) Limited | Agriculture & fishing | 1964 |
| DAJ Developments Limited | Construction | 1993 |
| Darby Plants Limited | Agriculture & fishing | 2001 |
| Daucina Charters PNG Ltd | Administrative & support | 2021 |